On other websites (4496)

• Ffmpeg won't copy excerpt of video correctly

  5 May 2022, by JR Jr.

  I am using a DOS batch to automate and copy excerpts of various high definition videos (mkv's with more than 1GB each).
The script is very convenient and runs fast and fine, but Ffmpeg is not doing its job correctly (it seems Murphy's law is inexorably enthralled into technology, things never come easy, which is why I love and hate it).

  


  Anyway, to cut a long story short, each time the batch job runs, a code like below is executed (pardon me the indiscrete folder name, it's about the 90's TV show, it's not porn!).

  


  call "C:\ffmpeg\bin\ffmpeg.exe" -y -i "D:\100\Sexo\S01\SATC - S01E03 - Bay of Married Pigs.mkv" -ss 00:18:05 -to 00:19:15 -codec copy "002-SATC - S01E03 - Bay of Married Pigs-00_18_05-00_19_15.mp4"


  


  The problem is that the first 6 seconds or so of the resulting video has no video, only audio with a frozen image that only starts to move after about 6 seconds, which is a huge defect, not to mention very annoying (a big let down, after all my meticulous scripting work :(). And this happens for most of the files, except a few ones.

  


  Even though this is copying and changing the format from mkv to mp4, per another thread on this site (https://askubuntu.com/questions/396883/how-to-simply-convert-video-files-i-e-mkv-to-mp4), this is not re-encoding, so this is not the issue. Actually, the same problem occurs even if I don't change the format from mkv to mp4.

  


  Even though I foresee a "there's no way to fix this", let me ask: is there a way to fix this? Hopefully there is a way.

  


• Why does FFMpeg not apply a video filter on a video input?

  8 November 2020, by blackirishman

  I am using ffmpeg to capture SDI audio video and pass it to named pipes. I wish to convert/specify the luminance range of the incoming video. Normally when publishing to an RTMP server I can specify -vf "in_range=full:out_range:limited" and that corrects my input range problem. This doesn't make a difference in the below example. Any ideas as to why?

  


  ffmpeg -y -format_code 23ps -f decklink -channels 2 -i "UltraStudio Recorder 3G" -r 24000/1001 -s 1280x720 -vf "in_range=full:out_range:limited" -map 0:a:0 -f s16le -ar 48000 -ac 2 unix:///var/folders/4q/2_zlrlbx4vj5gmm3xwjp7t8r0000gp/T/CoreFxPipe_ffcapture_pcm_68975ac4 -map 0:v:0 -f yuv4mpegpipe -pix_fmt yuv420p unix:///var/folders/4q/2_zlrlbx4vj5gmm3xwjp7t8r0000gp/T/CoreFxPipe_ffcapture_i420_648c8512

ffmpeg version 4.2.2 Copyright (c) 2000-2019 the FFmpeg developers
  built with Apple clang version 11.0.3 (clang-1103.0.32.29)
  configuration: --prefix=/usr/local --pkg-config-flags=--static --extra-cflags='-fno-stack-check -I/Users/me/Documents/working_vid_capture/ffmpeg_build/include -I/Users/me/Documents/working_vid_capture/BDS/Mac/include' --extra-ldflags=-L/Users/me/Documents/working_vid_capture/ffmpeg_build/lib --extra-libs='-lpthread -lm' --bindir=/Users/patrickcusack/Documents/working_vid_capture/ffmpeg_build/bin --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-nonfree --enable-decklink
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
[decklink @ 0x7f816e810e00] Found Decklink mode 1920 x 1080 with rate 23.98
[decklink @ 0x7f816e810e00] Frame received (#1) - No input signal detected - Frames dropped 1
Guessed Channel Layout for Input Stream #0.0 : stereo


  


• How to play mp4 video file with HTML5 video tag on iOS (iPhone and iPad)?

  22 April 2015, by Mokielas

  I want to display HTML5 video to my users using the video tag. For Firefox, Chrome and Opera WEBM works as expected. In Safari on Windows and Mac my MP4 version works, too. The only problem I’m experiencing is, that it won’t play on iPad and iPhone (Safari of course).

  Create video

  The MP4 (h.264 + acc-lc) is converted like this (with profile: baseline and level 3.0 for maximum compatibility with iOS):

  • Stream #0:0(eng): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 640x352, 198 kb/s, 17 fps, 17 tbr, 17408 tbn, 34 tbc (default)
  • Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 56 kb/s (default)

  Edit: Whole ffprobe output (slight changes in bitrate etc. to the above mentioned):

  Metadata:
  
  major_brand     : isom
  
  minor_version   : 512
  
  compatible_brands: isomiso2avc1mp41
  
  encoder         : Lavf56.30.100
  
  Duration: 00:01:00.05, start: 0.046440, bitrate: 289 kb/s
  
  Stream #0:0(eng): Video: h264 (Constrained Baseline) 
  
  (avc1 /0x31637661), yuv420p, 640x352, 198 kb/s, 25 fps, 25 tbr, 
  
  12800 tbn, 50 tbc (default)
  
  Metadata:
  
    handler_name    : VideoHandler
  
  Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, 
  
  stereo, fltp, 85 kb/s (default)
  
  Metadata:
  
    handler_name    : SoundHandler

  I found various requirements for iOS devices like this and this, also someone mentioned to add the yuv420p pixel format when converting.

  In fact the ffmpeg cmd looks like this:

  ffmpeg -i __inputfile__ -vcodec libx264 -pix_fmt yuv420p -profile:v baseline -level 3.0 -b:v 200K -r 17 -bt 800K -c:a libfdk_aac -b:a 85k -ar 44100 -y __outputfile_lowversion__.mp4

  Display video

  With Modernizr I detect which format is "supported" and add it to the src or the video tag. Last thing is adding the right MIME type. For mp4 I add type="video/mp4". The full code for the video tag is:

  <video class="p-video" preload="auto" autoplay="" type="video/mp4" src="http://full.url/to/video_low.mp4"></video>

  I tried various ways: own implementation with own interface, controls and stuff from browser vendors and video.js just to check whether i’m too studip for this. All work in the environments listed above except for iPhone and iPad.

  I read this article on Video on the web, especially this part and only serve the "right" file with the "right" type without a posterattribute set.

  My Apache has

  AddType video/mp4                      mp4 m4v f4v f4p
  
  AddType video/ogg                      ogv
  
  AddType video/webm                     webm

  And byte-ranges are enabled. This is needed to get partial content from the server.

  Has anyone a clue what’s going on there? Thanks in advance!

  Edit: Safari and Chrome both throw MEDIA_ERR_SRC_NOT_SUPPORTED Error on iPad. There must be an issue with the encoding.